# Understanding Dali2 D4i, 202 memory bank energy data

Below is a log from memory bank 202:

Bank [202] , Loc[0x04]: 255

Bank [202] , Loc[0x05]: 0

Bank [202] , Loc[0x06]: 0

Bank [202] , Loc[0x07]: 0

Bank [202] , Loc[0x08]: 1

Bank [202] , Loc[0x09]: 49

Bank [202] , Loc[0x0A]: 107

Bank [202] , Loc[0x0B]: 255

Bank [202] , Loc[0x0C]: 0

Bank [202] , Loc[0x0D]: 0

Bank [202] , Loc[0x0E]: 0

Bank [202] , Loc[0x0F]: 49

Above are the values that I am getting from memory bank 202. luminaire was running at 38.9 W AC. Can some one help me interpret active energy data.

Did you do a "refresh" before reading the values? when you change the light levels you have to do a relatch of the bank so setting lock byte again to 0xAA as described here

• If you could please copy and paste the text instead of taking a screenshot of the text, it would be better, since it makes the text more searchable, and findable on search engines, and also makes the font look more uniform across the site. – Nike Dattani Apr 23 at 0:56

My guess based on the value and what you've measured is 36.3418Wh. This was having the lsb as a fraction. Thus: 1 x 256 + 49 x 1 + 107/256 = 363.418. The scale is -1 (255), so multiply that by 0.1 gives us 36.3418 Wh. That lines up pretty close to your measurement.

Applying the same rules to Active Power doesn't seem to come up with anything sensible.

Scale Factor For Active Energy Bank [202] , Loc[0x04]: 255

255 means -1, so 10^-1 Wh = 0.1 Wh

Active Energy MSB Bank [202] , Loc[0x05]: 0

Bank [202] , Loc[0x06]: 0

Bank [202] , Loc[0x07]: 0

Bank [202] , Loc[0x08]: 1

Bank [202] , Loc[0x09]: 49

Active Energy LSB Bank [202] , Loc[0x0A]: 107

So active energy raw value = 0x00 00 00 01 31 68 which is 0x13168 = 78184 decimal. Then scale using Loc 0x04 in 0.1 Wh so 7818.4 Wh

Scale Factor for Active Power Bank [202] , Loc[0x0B]: 255

255 means -1 so 10^-1 W = 0.1 W

Active Power MSB Bank [202] , Loc[0x0C]: 0

Bank [202] , Loc[0x0D]: 0

Bank [202] , Loc[0x0E]: 0

Active Power LSB Bank [202] , Loc[0x0F]: 49

so active power raw value = 0x00 00 00 49 = 73 then scale using Loc 0x0B is 0.1 W so 7.3 W

The scale factor is for the whole raw value, not just the LSB.

• Hi Martin, I have used the same methodology of your's to retrieve the values. The but the values arrived doesn't match the actual values. Even with the actual power calculation that you have done. the value arrived is 7.3 W, But power meter reading shows 38.9 W AC, which is closer to the actual value. Am i missing something in this case. Thanks – adharsh ramanathan Apr 12 at 7:11
• The memory bank reading is for that gear plus the lamps it is driving, plus any power drawn from the gear's own DALI bus power supply & Aux supply if applicable, so if you are only looking at the lamp's rated power you would get a discrepancy, or if there are multiple gear connected to your measuring instrument. Some difference could be due to power factor - is your instrument showing VA not W? Memory Bank 203, optional, gives apparent power and would be interesting to compare. If you can account for all those, contact the manufacturer with the results and raw values, describing your setup. – Martin Apr 12 at 9:39

I'd interpret that as follows I may be wrong.

ENERGY:

0X04 = -1 twos complement = scale factor 10^-1 = 0.1.

0X08/09/0A= 1 49 107 = 1 X 6553.

• 49 X 256.
• 107

POWER:

Scale factor 0.1 as before Power = 49 X 0.1 = 4.9

That does not seem to match your expected power.